Increasingly, resources such as heavy crude oils, tar sands, shale oils, and coal are being utilized as hydrocarbon sources due to decreasing availability of easily accessed light sweet crude oil reservoirs. These resources are disadvantaged relative to light sweet crude oils, often containing significant amounts of sulfur, nitrogen, metals, and heavy hydrocarbon fractions including residue and asphaltenes. The disadvantaged crudes typically require a considerable amount of upgrading in order to obtain useful hydrocarbon products therefrom.
Numerous catalysts have been developed for catalytically hydrocracking and hydrotreating disadvantaged hydrocarbon feedstocks. Typically, these catalysts contain a Group VIB or Group VIII metal supported on a carrier formed of alumina, silica, or alumina-silica. Such catalysts are commonly sulfided to activate the catalyst, either before contacting the catalyst with a disadvantaged hydrocarbon feed or in situ with the disadvantaged hydrocarbon feed.
Applicants have discovered that a bimetallic or polymetallic thiometallate or selenometallate material is an exceptionally good catalyst for upgrading disadvantaged hydrocarbon feedstocks, particularly for converting all or substantially all heavy fractions such as residue and asphaltenes in the feedstock to lighter fractions while forming little or no coke. In particular, Applicants have discovered that bimetallic tetrathiomolybdates, tetrathiotungstates, and tetrathiovanadates and/or polymetallic tetrathiomolybdates, tetrathiotungstates, and tetrathiovanadates and their tetraseleno-analogs are especially effective for hydrocracking disadvantaged hydrocarbon feedstocks to upgrade the feedstocks.
Ammonium and alkylammonium thiometallates have been used as precursors to produce metal sulfides. For example, tetraalkylammonium thiomolybdate, tetraalkylammonium thiotungstate, and ammonium thiomolybdate precursor compounds have been treated at temperatures of above 350° C. to thermally decompose the precursor compounds to produce MoS2 and WS2 disulfides having predicable stoichiometry that have a high surface area and show substantial hydrodesulfurization and hydrodenitrogenation catalytic activity. Ammonium thiometallates have also been used as precursors to produce bimetallic compounds in an organic solvent. For example, copper thiometallates and copper selenometallates have been produced using a solvothermal method by reacting (NH4)2MoS4, (NH4)2WS4, (PPh4)2MoSe4, or (PPh4)2WSe4 with copper borofluoride salts in organic solvents at temperatures of 110° C. or above in an autoclave at autogenous pressures. Iron-molybdenum sulfide compounds have been produced by dissolving (NH4)2MoS4 in an organic chelating solution of diethylenetriamine (dien) and slowly adding an iron salt in a 10% aqueous dien solution to precipitate a hydrodenitrogenation catalyst precursor. The precursor is thermally decomposed to remove organic ligand constituents and sulfactivate the catalyst. Such methods may be impractical for producing high yields of bimetallic or polymetallic thiometallates having a high surface area in a cost effective manner due to the temperatures, pressures, and solvents required, or due to the nature of the products themselves.
A method of preparing copper tetrathiomolybdates from ammonium tetrathiomolybdates and a copper salt is described in The Copper-Molybdenum Antagonism in Ruminants. III. Reaction of Copper(II) with Tetrathiomolybdate(VI), Laurie, Pratt, & Raynor, Inorganica Chimica Acta, 123 (1986) 193-196. Aqueous solutions of reactants CuSO4.5H2O and M2I-MoS4 (MI=NH4+, Et4N+, or Na+) and (NH4)2MoS4 were mixed to form a solid product which was collected by filtration, washed, and then dried. The solid product contained two materials, a composition MICuMoS4 (where MI is the MI included in the tetrathiomolybdate reactant) and a composition CuMoS4-xOx, where x=2 or 3.
Improved processes are desirable for producing thiometallate or selenometallate materials, particularly bimetallic or polymetallic thiometallate or selenometallate materials.